Control device



N0V 3 1942 G. c. AFuvISTRoNGv 2,300,900

CONTROL DEVICE Filed Oct. 21, 1938 4 Sheets-Sheet 1 Nov. 3, 1942. G. c.ARMSTRONG 2,300.900

CONTROL DEVICE l Filed Oct. 21, 1958 4 Sheets-Sheet v2 WITNESSES:INVENTOR @d-fr www' 3' @9060 @fir/500W BY fauf W@ ATTORNEY NOV 3, 1942G. c. ARMSTRONG 2,300,900L

CONTROL DEVICE Filed Oct. 21, 1958 4 Sheets-Sheet 3 I ATTORNEY Nov. 3,1942. G. c. ARMSTRQNG 2,300,900

CONTROL DEVICE Filed Oct. 21, 1938 4 Sheets-Sheet 4 F'y: .TIME-2QWITNESSES: INVENTOR W71?" FM 6' TORNEY Patented Nov. 3, 1942 CONTROLDEVICE George C. Armstrong, Wllkinsburg, Pa., assignor to WestinghouseElectric Manufacturing Company, East Pittsburgh, Pa., a corporation ofPennsylvania Application october zi. ma, sei-iai Na man icl. zoo-ss)Hollins.

My invention relates to control devices and more particularly to controldevices for actuating over-load relays, circuit-breaker-trip devices,measuring or indicating instniments or the like.

In my application Serial No. 139,978, flied April 30, 1937, and entitledControl devices, which application became Patent No. 2,162,521 on June13, 1939, I disclose certain details of construction of a thermal relayor control device suitable for use as a motor starter, in whichheat-responsive elements are provided asia means for procuring a moreaccurate indication of the thermal condition of the motor and therebyproviding by such indicated condition a more accurate control of themotor 'before dangerous conditions may be 'developed in the motor.

In that previous application, my invention was particularly directed tothe type of heat-responsive device, particularly a bimetsl member havinga larger heatstorage capacity or mass while at the same time retainingthe sensitivity of a bimetal member of lesser mass. l

In the present application, I am concerned with providing an arrangementthat shall establish a modified inverse time characteristic in the.operation of the thermally responsive bimetal element, either withoutincreasing the normal mass or heat storage capacity of that thermallyresponsive element, or, in conjunction with such changes, to furthermodify the time characteris tics of the relay.

I am also concerned in this `application with the provision of means forinstantaneously tripping the device upon the occurrence of short-circuitconditions, or extremely rapid excessive current changes.

To increase the operating time of s bimetallic heat-responsive element,one method is to increase its mass so that it will take longer for suchelement to change its eifective temperature. If the mass of a bimetallicelement is increased by merely increasing the thickness thereof, thetemperature necessary for the operation of such an element will likewisebe increased for s given length of such element. This condition wouldthen require an increased wattage for a given length, or would requirean element of increased length with the same heat supply, to produce agiven deflection. However, since the physical characteristics of thosedevices which use a bimetallic element impose certain limits on the sizeof such element, or the axnountof heat to be supplied to such element,such limitations have presented a problem in establishing and procuringproper desirable operating time ycharacteristics in a bimetal element. fe It is accordingly an object of my invention to provide a modifiedbimetallic heat-responsive device which shall be small.' compact andsensitive, and which shall be capable'of providing an inverse timeelement characteristic, that is, a time interval in its operation; thatshall be disproportionately greater at higher current values.

"I'hus, one of the principal objects of nLv invention is to provide anarrangement for increasing the time delay in a thermal overload relaywithout modifying the mass or thermal capacity of a standard thermallyresponsive unit that is normally. employed in a manufactured line -ofsuch relays or control devices; or, to provide an arrangement forincreasing the time element or interval of operation beyond that whichcould be procured by modifying the mass of thermal capacity of thethermally responsive unit. v

A further object of my invention isAV Vto provide an instantaneous tripdevice for controlling the operation of the relay in conjunction withthe control action established by the heat-responsive "element v A stillfurther object ofthe invention is to provide joint meansto-disproportionately control the energisation of the heat-.responsivedeviceV according to the circuit current, and cooperating means whichshall be controlled by such energizing means to distinguish betweennormal overload conditions and short-circuit conditions, and

to efl'ect instantaneous tripping of the device` 3s upon the occurrenceof short-circuit conditions.

In the thermal relay to which I have applied my invention herein, forthe purpose of speciiic illustration, the thermally responsive blmetalis heated by a heater energized from the circuit to be protected. In thecase oi heavy overloads or short-circuits, the heater currents might behigh enough to burn out the heaters. Protection for thefheaters againstexcessive current is therefo desirable and necessary.

di A saturating transformer may be used between the circuit and theheater, and it introduces a means of protection by reducing the value ofhigh current supplied to the heater, but, in some cases, the currentmayk still be high enough to burn out 50 the heater.l Moreover, where itis applied to exu 'Overheated unless it be of excessive size, and

former, a smaller transformer may be employed.

In order to utilize the saturated condition of the transformer as anindication and control func tion, I provide a pivoted amature adjacentthe transformer structure to be attracted by the stray or leakage fluxof the transformer, when the transformer core saturates, and arrangedthe armature to serve as a trip attachment for the relay, or for anexternal circuit to a circuit breaker.

Instead of using a saturable transformer, I.

may employ a saturable reactor or inductive shunt, which may be'considered a one-to-one "auto-transformer, for connection across aheater.

Tbeshuntmaybemountedontherelaywithoutrcquiringanincreaseinmountingspaceorin mmmuntnsimuulymvidsd' with aplvoted armature, which isl actuated by the dray ux held, aftersaturatiom'to trip the relay contacts that control tective circuitbreaker.

Other obiects of my invention will either be pointed out lpeically inthe course of the following dcription of a device embodying myinvolition, or will be apparent from such descriptial the circuit to apro- !n'tbe accompanying drawings:

ligure 1 is a plan viewof a relay provided with 40I a aaturable corereactor having an armature according to my invention;

Pig. 2 is a side elevational view of the relay shown in Fig. l, lookingat the left-hand side of the relay in Fil. l:

Pil. 2 is a vertical sectional view of the relay of Pig. 1. taken alongthe line lJI-HI in Fig. l;

Fig. 4 is a sectional view of the relay taken along the line IV-IV ofFig. l;

Pig. 5 is a view of one of the latching members as it appears in a viewoi' the relay shown in Hg. 2 taken along the line VV;

Fig. 0 is a side elevational view oi' a tripping latch release rodcontrolled by the amature of the saturating core reactor;

Hg. I is a sectional view of the relay of Fig. l taken along the lineVII--VII thereof to show the reset member i Hu. l, "2 and i0 are plan,and side views, respectively, of a saturable transformer provided withan armature responsive to stray nux for controlling contact members toan external circuit; and f Figa. 1l, 12 and 13 are simple diagrams ofcircuits containing thermal relays embodying the principles of myinvention.

Referring to the drawings, a thermal overload relay i is showncomprising a base 2, a plurality of hut-responsive devices or bimetalmembers 2 and heaters I.

The heaters I are shown as channel-shaped radiant heaters removablyattached to terminal blocks II by means of shoulder screws I2. Thebimetallic device 2 may comprise one or `more 4separate bimetallicelements any may be rigidly `attached at one end to the latch members Bby suitable means such as rivets lllI and are located within thechannel-shaped radiant heaters l.

It is to be understood that the radiant heater I and the bimetallicmember l may be located within any desirable insulating fluid such asair, or a controlled atmosphere, and that such blmetallic structure willflex in response to the heated circumambient fluid. The actuatingelement l may be removably mounted upon the free end of the bimetallicmember 2, and may be held in swingable relation thereto by means of thehelical spring l attached at one end to the actuating element I and atthe other end to the stationary latch member l. The actuating element l,when in latched position, is held by spring l substantially normal tobase 2 with the upper end of the actuating element l held against ashoulder Il of the latch member l. The outer end ofthe latch member lextends through an aperture I4 in the actuating element I.

The cross-bar il is swingably mounted upon v the base 2 by means oflevers II and Ila, which are rotatably mounted upon brackets such as il(see Fig. 7). A contact Il is rigidly attached to the lever Ila andengages a contact 2l rigidly attached to the free end of a flexibleresilient finger 2|, which in turn is rigidly attached at its other endto bracket 22.

While the bimetallic structure 2 iiexes downwardly 'or -away from thestationary latch member l, due to the heat radiated from heater l, the

actuating element l is likewise moved from the latch member l along itsshoulder portion Il and toward the base 2 until the aperture il becomesfree of the shoulder portion i2 which in turn, permits the spring 1 topull the actuating element l upwardly along the latch member t, andabout the free end of the bimetal 2 as a center, as viewed in Fig. 2.When the actuating element l is released at latch lmember t, it engagesthe cross-bar i8, and moves the cross-bar Il with it in response tospring 1. When the cross-bar il is swung upwardly, as hereinabovedescribed, the levers i1 and Ila are correspondingly rotated about theirrespective pivots on brackets it, and disengage the contact i5 from thecontact 2li, while an extended lower arm portion 24 (Fig. 7) of lever ilcontacts a manual reset plunger 30 slidably mounted upon a bracket 32 ofa manual resetting device 35. At the same time, an extended arm 25 oflever Ha compresses a reaction compression spring 26 (Fig. 4)

The operation of the device'may be restated brieily as follows:

The lever I'ia and a similarly plvoted lever I1 carry a cross bar IBwhich is engaged by actuating elements l, 5 and E! to move the switchlI--ll to open position. The actuating elements are movable by springs1, l and 59 (which are stronger than springs 28, and which will readilyovercome their biasing action). The actuating elements, however, arenormally held against actuation by the stationary latch members S, l andthe pivoted latch member 52. The latch member I2 is tripped by one of`the armatures Il acting through tht rod 50 (as will be described morefully hereinafter). Each oi the actuating elements B, l may be movedlongitudinally towards support 2 by its respective thermostat l to freeit from the restraint of the corresponding latch member.

To reset the relay and reestab1ish contact between the contacts I! and2D, the plunger l0 of the manual resetting device 35 is forced inwardly-against the action of a spring 3|, causing the extended arm portion 24of lever I1 to return to its normal position substantially parallel tothe base 2. Simultaneously with such action, the cross-bar I5 isreturned to its normal operating position, re-engaging contacts I9 and20, and relatching operating members 5 uponthe shoulder portion I3 ofthe latch members 5. The reaction spring 2l maintains the normal contactpressure.

When the channel-shaped radiant heaters 4 are operatively connected witha power circuit by means of the terminal blocks I I and the shoulderscrews I2, the heat radiated therefrom is substantially proportional tothe power fluctuations of such circuit. Consequently, the bimetallicstructures 3, being located within the respective radiant heaters 4,willlikewise respond to the power fluctuations of such circuit.v Thecontrolcircuit contact members I3-2U may be connected to control thecircuit of an external power circuit controlling device, to protect anassociated motor and the associated reactors and the relay againstoverheating.

To adapt a thermal relay, as hereinabove described, to thecharacteristics of various power circuits, it has been the practice toconnect the radiant heaters 4 of such relays to such power circuits bymeans of saturating current transiormers. By the use of suchtransformers, the amount of power `directly applied to the radiantheaters 4 may be adjusted and limited to the requirements of theparticular circuit and relay.

' Consequently, the relay may operate with any set time characteristicfora given load or upon a delayed time characteristic with the sameload, providing th transformers or the heaters operativelyassociatedtherewith have been correspondingly changed. s

In the present case, I have applied a saturating core reactor directlyacross the terminals' of the relay, where the heaters 4 are alreadyconnected. Such connections do not require any disturbance of theexisting connections of the heaters to the terminals. and permit theready application of such saturating core reactors to relays or otherdevices already in service, without requiring the disturbanceof thoseconnections. Such reactors also permit a more flexible adaptation of thecontrol devices for various applications by modifying the design of thereactors and their characteristics to establish a desired corelationwith the relays.

The reactor is, of course, smaller than a transformer since it embodiesonly one winding instead of two, and carries only a very small fractionof the line current except at high overloads. A disadvantage of such a'saturating transformer is that it is bulky and expensive. Moreover, itcannot be readily .applied to control devices already in service, or toalready designed devices,

without requiring a modification of the circuit of short-circuitconditions.

The reactor 4II in Fig. 2 is shown on the lefthand bracket or frame 4Iwhich is provided for the trip-restraining bracket 5. The reactor 4Icomprises brieiiy a coil 42 and an encircling laminated magneticstructure 43, upon which is pivotallysupported a magnetizable armature44 that is biased away from the magnetizable structure. 43 by a biasingspring 45 and limited to a maximum separation by a non-magnetizable stoparm 46. The biased edge of the armature 44 is provided with an inclinedrow of openings 41 to permit the biasing spring 45 to be selectively andadjustably positioned.

The outer end of the pivoted armature 44 is disposed in position toestablish a cooperative control relationship with a transversely locatedtripping rod 50 that is supported for axial movement between the twostationary latch members '6 on each side of the control device, disposeddirectly above the respective heaters 4. The trip rod is preferably ofnon-magnetizable and electrically insulating material, and may be made,for example, of material sold under the trade-name Micarta, or of somesimilar or equivalent functioning insulation material, and is normallybiased by a biasing spring 5I to its extreme right position. In thatextreme right position, which is the normally untripped position, thetrip rod 50, as shown in Figs. l and 6, holds a centrally located andpivotally mounted latch member 52' in position to control an actuatingelement 53, similar to the two actuating elements 5 that are associatedwith the bimetal elements 3.

The trip rod 5I! is provided with two peripheral annular grooves 55 and55 into which the respective armatures 44 of the two saturable reactors40 normally extend. A similar peripheral groove 51 is provided intowhich the rear arm 52a, 'of the latch member 52, may fall (Figs. l and6) -to release the actuating element 53, at the shoulder 52h of thefront arm 52e, when the trip rod 5l is shifted axially, against itsbiasing spring 5I, .by

-either one oi the armatures 44 of the respective reactors.

In the normal untripped position of the relay,

as shown in Fig. 1, the rear arm 52a of the lever 52 (Fig. 6) rests uponthe peripheral surface .5l of the transverse trip rod 50 in such manneras to hold theactuating element 53 against movement in response to itsspring 53. The inner end of the actuating element 53 is pivotallysupported on a stationary extension ringer 50 on the bracket 6I whoseside arm 52 serves also to pivotally support the latch member 52. Theouter end of the actuating element 53 is provided with an opening 53athrough which the lower end 52o of the latch member extends. Asillustrated in Fig. 6, the actuating element 53 rests against the smallshoulder 52h which holds the actuating element 53 against movementaround the pivotal linger 6D. as a center.

To release the actuating element 53, the trip rod 50 must be actuated byone of the reactor `armatures 44. During normal load conditions,

practically the entire load current will pass through the heaterswhereas only a very small current will pass through the reactors, inview of the relatively high lxnpedance of the reactor compared to theresistance of the heaters, which are non-inductive. For normal loadconditions, the bimetallic device 3 will respond to the heaters tocontrol the operation of the relay.

As the load current increases to values above normal load values, thecurrent distribution between the heaters and the reactors will change.As the load current increases, the proportionate division of loadcurrent through the reactor tends.

to'establish a saturated condition in the reactor.

Buch saturated condition in turn tends to diminish the impedance of thereactor. Consequently, as the impedance of the reactor diminishes, therelationship between the impedance of the reactor and the resistance ofthe heater becomes modiiied and a proportionately greater portion of theload current traverses the reactor.

When the reactor becomes fully saturated by its current, an abnormalcondition is indicated, at which time it is desired to operate the relayinstantly to open the circuit to the associated motor.

At this time, in view of the saturated condition of the reactor core II,sumcient stray flux is generated to attract the amature I4 and to causeit to actuate the trip rod Il. Depending upon the condition of thecircuit to the motor. that is, whether it is balanced or unbalanced, theheaters and the associated reactors may be similarly and equallyenergized or unequally energized. Thus, either reactor armature, or bothreactor armaturea, will operate the trip rod Il to permit the latchmember l1 to rotate about its pivot Il sufnciently to permit theactuating element I to be moved by the biasing spring Il to operate thecross-bar I. and to disengage the contacts Il and Il.

When the latch member l! is released by the trip rod Il, and rotatesabout its pivot Il, due to the off-center turning force of the actuatingelement Il against the shoulder B2b, the shoulder B2b rises until itreaches the opening lla in the actuating element Il, whereupon theactuating element I8 is freed to turn about its pivotal support fingerIl to engage bar Il and to separate contacts Il and Il. The upper edgeof the opening Ila then engages the back, or top edge, 52d of the latchmember l2.

When the relay is subsequently reset, and the crom-bar Il moved forwardagain to engage and move the achratlng element Il downward to its resetposition, the outer end c of the actuating element will engage theprojection Ile of the latch member Il will turn the latch member l!enough to raise the back arm lia out of the slot inthetrlprodllandallowthetriprodwresume its non-operated reset position tohold thelatch member l2 in effective position. While the trip rod Il resetsitself, the actuating element ill continues to move forward as pushed bythe cross-bar Il. The top edge of the opening lla is high enough to moveover the top projection lle of the actuating element iront l2c when thelatch member l! is rotated to reset position, in

order to permit the cross-bar Il to move forward sumciently, onresetting, to be able to reset the right and the left-hand actuatingelements l and I3 without requiring the alignment of the actuatingelements to be extremely accurate.

'I'he contacts Il and Il open an external circuit. as illustrated. forexample, in Fig. 1l, to deenergize the energizing and holding coil Il onthe contactar switch l! connecting the supply line l1 to the controlmotor Il.

The principle o! operation of the relay is generally indicated by theschematic arrangement of corresponding elements of the relay in thediagram of Fig. ll. As is evident from that diagram, operation of abimetallic element I, or of ton Il is operated. as previously explainedin Fig. 7. The remaining details of the resetting structure of Figs. 4and 7 are schematically illustrated in the diagram of Fig. 1l.

After the relay has been reset, the contacter switch It may be reclosedby momentarily energizing 4the circuit of the operating coil 65 througha push button 68. The contactor G6 then locks itself in through its backinterlock contact 10.

By means of the arrangement just illustrated, the relay may be operatedby the direct trip armature of the reactor 40 to open the holdingcircuit of the contactor, thereby disconnecting the motor on theoccurrence of excessive load or short circuit conditions.

In Fig. 13, I have illustrated a modiiied control arrangement whereinthe armature M associated withthe reactor 4l controls a. switch 12 for apair of contacts directly, so that upon the occurrence of the saturatedcondition in the reactor Il, attended by attraction of the armature 44,the switch 12 will be opened to deenergize the associated circuit todisconnect the motor 8l. In this case, the contact switch 12 isillustrated as controlling the circuit of the contacter 6B in serieswith a similar switch 1l controlled by the bimetal member I.

Although I have illustrated the application of a reactor to the thermalrelay described herein, merely to show a preferred structure, the sameprinciple of my invention may be applied to a combination employing asaturable transformer, with two windings, in the same manner as isillustrated in the application to a single winding reactor.

For the modification involving a transformer, my invention contemplatesdisposing a pivoted magnetizable armature adjacent tho magnetic core ofthe transformer where the armature will be attracted by the stray fluxafter saturation.

As shown in Figs. 8, 9 and 10, a transformer Il the primary winding ofwhich carries the :motor current, is provided with a magnetic core Il tobecome saturated at a certain load current. An armature l2, adjacent thecore Kil is biased on spring ill against a spacer l! and is attracted bystray flux after saturation. The armature I2 may be arranged, as shown,to actuate a lever Il, pivoted on pin 82, thereby operating a bridgingcontact It to control the opening or closing oi' an external circuit`between two cooperating stationary contact members I8 and I1. ThoseContact members 8E and I1 may be part of a thermal overload motorprotective relay mounted on the side or the transformer and providedwith a heater "connected in the secondary circuit of the transformer, byconductors s,

Il, to heat a bimeial member, not shown, which, at moderately highoverload currents will ellect tripping of the contact member B5. Atextremely high overload currents, the magnetic structure The armature Mmay be arranged to open them circuit, or to closel the circuit, betweenthe contacts I6 and I1. im Fig. l2 I have illustrated, in diagram, asinniivle circuit in which such a pivoted armature, msociated with atransformer, closes the circl between the associated contacts. In the arungement shown in Fig. 12, the circuit controllori `and established bythose contacts serves to shunt the heater associated with the bimetalmember in order to provide protecon as are imposed by the prior art andthe tion for the heater against excessive load cur- Y to open thecircuit of the main contactor switch l! by the relay switch vIl inresponse to the operation of bimetall element M associated with theheater 95.

Various modiiications may be made in the de-v vices embodying myinvention, without departing from the spirit and scope thereof, and Idesire that only such limitations shall be placed thereappended claims.I claim as my invention: A i. A relay foran electric circuit comprising,

` in combination, a saturable electromagnetic dev vice including awinding, a heater resistor in electrical relationship with said winding,thereby receiving a proportionate share of an incoming current, abimetallic thermal responsive element adjacent said heater resistor, anelectrical switch, operating means actuable by said ther--Y malresponsive `element when a 'predetermined lvalue oi incoming current isattained, for operating said switch and a second operating means forsaid switch actuable as the result of saturation ot said electromagneticdevice when the incoming current exceeds said predetermined value.

said contact members, biasing means tor said pivoted supporting means. alatching 'element for normally retaining said actuating element andwhich is releasable by the heat responsive device for permittingmovement oi said pivoted supporting means 'by said actuating element inopposition to said'fbiasing means. reactor means paralleling the heatingelement and having a core with saturating characteristics which permitthe maior portion or a current to traverse the heating element at lowcurrent values below satura. tion and which permit the reactor totransmit a greater proportion of current at high current values abovesaturation, whereby the relay may have an inverse time elementcharacteristic, a second latching means, a second actuating member, andmeansvresponsive to short-circuit saturation characteristics oi thereactor for controlling said sc-.cond latching means to release saidsecond actuating member which in turn operates said pivoted contactsupporting means and selectively operates said contact members. e

5.' A relay provided with a heat-responsive device and a heating elementtherefor, contact 2. A relay for an electric circuit comprising,

in combination, a saturable electromagnetic deviceincluding a winding, aheater resistor connected in parallel with said winding, therebyreceiving a proportionate share oi an incoming current, a thermalresponsive element adjacent y said .heater resistor, an electricalswitch, opei"atV ing means actuable by said thermal responsive elementwhen a predetermined value of incom` ing current is attained, foroperating said switch and a second operating means actuablel as theresult of saturation oi said electromagnetic device when the incomingcurrent exceeds said premembers, actuating means ior disenglsinl one ofsaid contact members from the other, pivoted supporting means for one otsaid contact members, latching means for normally restraining l saidactuating ymeans from engagement with said pivoted supporting means,reactor means paraileling the heating element and having a core withsaturating characteristics which permit the major portion ot a currentto traverse the heating element at lowcurrent values below saturationoi' the core and which permit the reactor to transmit a greaterproportion or the current at high current values aboveA saturation,whereby the relay may have an inverse time element characteristic, apivoted armature adjacent theredetermined value, said second operatingmeans including parts which are common with said ilrst operating means,said second operating means also being effective to operate saidelectrical switch,

3. A relay for an electric circuit comprising, in combination, asaturable .electromagnetic device including a winding, a heater resistorconnected in parallel with said winding, thereby receiving aproportionate share of an incoming current, a thermal responsive elementadjacent said heater resistor, an electrical switch, pivoted meansincluding a cross bar for supporting one oi thecontact elements of saidswitch, actuating means normally biased for moving said cross bar tooperate said switch, latch means for normally restraining said bias,said thermal responsive element being eiiective as the result oi avpredetermined amount of incoming current and heat developed by saidresistor to unlatch said latch means to remove said restraint, andoperating actor core and means controlled by the armature roi'controlling said latching means toroperate said contact supportingmeans, and means inciuding a second latching means and being contrailedby said heat responsive device for alternately operating. said contactsupporting o. A relay provided with va heat-responi'iive de vice and aheating element tnereior, contact members, means biasing them to mgagedposition, `supporting means ior one ot said contact members, actuatingmeans, latching means tor` said actuating means, a second biasing meansIor biasing said actuating means so as to eiiect opening or said contactmembers, reactor means paralleling the heating element and having a .v

core with saturating characteristics which permit the major portion of acurrent to traverse the heating element at low circuit current valuesbelow saturation and which permit the reactor.

to transmit a greater proportion of the current at high'current valuesabove saturation, whereby the relay may have an inverse time elementcharacteristic, said heat-responsive device being eiiective i'orreleasing the actuating means, a pivoted armature adgacent the reactorcore, a second actuating means, and means controlled by the armaturer'or releasing the second actuating means to move the supporting meansthereby opening said contact members.

'l'. An overload relay comprising cooperating contact members. meansbiasing them closed, actuating means to eiect opening of said contactmembers and latching means for normally latchingr said actuating means,a heating resistor and a neat-responsive device responsive to anincoming current for controlling the latching means, anci aninstantaneous trip device including a msgnsuefussisghnsnuo sie heatingre- `lis'toralildisi'esnonsivetorapidcur'x-entincx'easea-abovsaoertainvaiue for eilecting operation o! saisioontactnmenxbsrs.`

8. An overload relay comprlsingcooperating *l oontact'members, actuatingmeans for operating oneoisaidoontactmemberaandlatchingmeans normallyrendering said actuatina means ineiiective to operate said contactmembers, a heater and a beat-responsive device responsive to a currentfor controlling the latohing means, an intrip device including a secondlatch- 1 ing means and responsive to rapid increases o! current above acertain value for controlling ,said second latching means, saidinstantaneous comprising a reactor with a saturating gtonormallyrendersald actuating means ineilective to open said contactmembers, heat-responsivemeanstoreleasethelatchingmesnaaheatertobemergiaedbyacurrenttoheattheheatresponsive means, a reactor shuntbridging the heaterandhavingacorethatwiilsaturateata predeterminedcurrentthroughthe reactor shunt,

' circuit current to heat the heat-responsive means,

andmeanscontrollcdhvthereactorshuntior` alternately operating saidcontact members.

10. An overload relay comprising contact members, actuating means foropening said contact l members, latehing means to normally render saidactuatingmeansinelectivetoopensaidcontact members,- heat-responsivemeans to release the latcbingmean's. absater'tobeenergisedbythe circuitcurrent tobeat the heat-responsive means. a reactor shunt bridaing theheater and having a core that will saturate at a predetermined currentthrough the reactor shunt, a second latching means, and means responsiveto the degree of energisation o! the reactor shunt for controlling saidsecond latching means so as to eilect opening o! said contact members.

. ll. An overload relay comprising contact members. actuating means foropening said contact members, iatching means to normally render saidactuating means incilective to open said contact members.beat-responsivemeans tc release theAlatchingineans,aheatertobeenergizedbythe a reactor shunt bridging theheater and having a core than will saturate at a predetermined currentthrough the reactor shunt, a second latching means, and means responsiveto energization oi the reactor shunt above saturation for controllingsaid second latching means so as to eilect opening of said contactmembers.

l2. An overload relay for an electric circuit, comprising contactmembers, actuating means for disengsging one oi said contact membersfrom the other, latching means normally rendering said actuating meansineilectiveto open said contact members, heat-responsive means torelease the latching means, means for increasing the normal time elemento! response oi the heatresponsive means at overload current values, asecond latching means, and means responsive to said time-increasingmeans for establishing direct-trip control of said second latching meansupon the occurrence of an excessive increase of said current so as toeffect opening oi said contact members.

13. An overload relay for an electric circuit, comprising a heater to beenergized by an incoming current, a heat-responsive element to be heatedthereby, a contact member operable by the heat-responsive element, andself-saturating means energized by said incoming current and operativeto modify the amount of current to the heater below certain incomingcurrent values to permit the heat responsive element to control thecontact member, and operative as the result o! saturation of saidsaturating means to establish independent action upon the contact membe-14. An overload relay for an electric circuit comprising a heater to beenergized by an incoming current, a heat-responsive element to be heatedthereby, a contact member operable by the heat-responsive element, andmeans energized by said incoming current and operative to modify theamount of current to the heater below certain incoming current values topermit the heatresponsive element to control the contact member, saidmeans embodying a saturable magnetic structure and an armatureresponsive to stray nux from said magnetic structure after saturationoccurring at said values, the armature operating directly andindependently ot the heat-responsive element to actuste the contactmember.

GEO. C. ARMSTRONG.

